Much electronic equipment is required to operate in environments where the air can pick up dust, lint, and other airborne impurities. If these contaminants are permitted to enter the cooling air passages, they might plug up the openings and reduce the air flow, causing overheating of the electronics. To prevent this from happening, air filters are often used. These air filters typically include a layer of demembraned polyurethane, paper, metal, or other plastic material woven or knitted and formed in an egg-crate or repeated pyramid shape.
In addition, in many telecommunications applications, the equipment also requires electromagnetic interference (EMI) protection, also known as RF shielding. These EMI protection devices generally include a metallic material mounted in a frame and inserted in the electronic enclosure.
When both characteristics of dust screening and RF filtration are required, two separate elements are installed, a metallic RF filter and an air filter to trap particulates. Alternatively, these devices can be formed of, for example, layers of corrugated aluminum mesh, which are so aligned to act as an air filter, or layers of crimped or expanded aluminum alloy. In this case, several layers of metallic material of differing aperture size, shape and spacing are required to be mounted in a frame for insertion into the electronic enclosure.
These prior art devices are relatively large in volume, need high maintenance, and are costly to produce.
Accordingly, there is a long felt need for a simple air filter with EMI protection properties.